New Blood Test May Help Curb Antibiotic Overprescribing

The gene signature technique proved to be 87% accurate in an observational study

A new blood test can tell with greater accuracy whether a respiratory illness is caused by a viral or bacterial infection. There is currently no highly accurate way to determine the exact cause of respiratory illness, which is one of the most common reasons people go to the doctor. Though still in its early stages, the new research — being conducted by Duke Medicine — could eventually lead to more precise treatment and a reduction in unnecessary antibiotic prescriptions.

From a small blood sample, researchers identify what they call ‘gene signatures'. These are patterns that reflect which genes in a patient are being turned on and off by a response to either a viral or bacterial infection; allowing the clinician a significantly greater level of accuracy when diagnosing an infection as viral or bacterial.

The gene signature technique proved to be 87% accurate in an observational study. Researchers were able to classify over 300 patients with flu viruses, rhinovirus, several strep bacteria and other common infections, as well as showing when no infection was present. The full study appeared in January's Science Translational Medicine

“Despite the fact that most of these infections are caused by viruses that don't get better with antibiotics, most patients end up getting an antibiotic,” said the study's lead author Ephraim Tsalik, MD, PhD. “There are risks to excess antibiotic use, both to the patient and to public health.”

Senior author Geoffrey S. Ginsburg, MD, PhD, pointed to the growing treatment options as a prime need for accurate diagnoses; he said “In the next 5 to 10 years, we will likely see new antiviral medications for common bugs like respiratory syncytial virus (RSV) and even rhinovirus and guiding treatment choices will be even more important.”

The current process which the researchers used to measure gene patterns can take up to 10 hours. The authors said they are in the process of developing a 1-hour test that could be used in clinics. “We are working to develop a test that could be run in most clinical labs on existing equipment,” said author Christopher W. Woods, MD. “We believe this could have a real impact on the appropriate use of antibiotics and guide the use of antiviral treatments in the future.”